This proposed project builds upon the current NIDA-funded study "Outcome Evaluation of a Prison-Based Therapeutic Community for Male and Female Substance Users" (PRISM). PRISM is an outcome evaluation of "Stay 'N Out", a prison-based therapeutic community for drug users (principally heroin addicts). Data from the current study show impressive reductions in recidivism and warrant further exploration. Data are available for 1,626 male and 398 female prison inmates who participated in the Stay 'N Out prison TC, three comparison treatment programs, and as 'waiting list' controls. All data are computerized and available for analyses. Major aims include identifying types of substance abusers who can and cannot benefit from Prison TC treatment and other types of prison-based drug treatment programs. Univariate and multivariate statistical techniques will be used to determine which client and program characteristics are associated with differential outcomes among incarcerated drug abuse populations.